Introduction to Cell and Tissue Structure Flashcards
Endocytosis
Plasma membrane folds to form intracellular vesicle that pinches off
Phagocytosis
Engulfing large particles
Pinocytosis
Engulfing small particles. Mediated via receptor/ligand binding.
Exocytosis
Intracellular vesicle fuses with the plasma membrane to release material inside the vesicle to extracellular space
Nucleus
Contains nucleoplasm and chromatin
Nuclear envelope
Double membrane with channels through both membranes (nuclear pores)
Nuclear lamina
Fibrous meshwork formed by proteins called lamins
Nuclear pore complex
Formed by specific proteins that regulate movement of material (RNAs, proteins, and ribosome subunits) in and out of nucleus
Nucleolus
Site of rRNA transcription and ribosome subunit assembly
Rough endoplasmic reticulum
Lipid synthesis, glycogenesis (making glycogen), detoxification (oxidation and methylation reactions), Ca2+ metabolism in striated muscle
Golgi apparatus
Ogliosaccharide chain processing, glycosylation and deglycosylation of proteins and lipids (adding and removing carbohydrates), assembly of proteoglycans (proteins with carbohydrates attached), phosphorylation and sulfation of proteoglycans and proteins, proteolytic processing of polypeptides (cleaving proteins to change function)
Endosomes
Associate with receptors to form coated pits and vesicles. Clathrins and clathrin-associated proteins form coat on the cytoplasmic surface of membrane.
Early endosomes
May still carry clathrin and surface receptor molecules. Internal acidification leads to receptor ligand separation.
Late endosomes
Shed cell surface related components (clathrin, receptors). Fuse with lysosomes.
Carrier vesicles (MVBs)
Transfer materials from early to late endosomes
Lysosomes
Have lytic enzymes. Fuse with late endosomes to form a secondary lysosome or phagolysosome to digest internalized material.
Peroxisomes
Major enzyme is catalase which metabolizes hydrogen peroxide by oxidation of organic substrates. Also contain enzymes for _-oxidation for long chain fatty acids. Some peroxisomes have crystalloid core (not humans) which helps with identification.
Mitochondria
Cristae are the site of proteins and enzymes for oxidative phosphorylation and ATPase synthetase complex. Inner membrane matrix contains enzymes for lipid synthesis and modification. Krebs cycle enzymes, DNA and RNA, ribosomes, and enzymes for protein synthesis. May store Ca2+.
Microfilaments
Actin (G-Actin) form two chain helical polymer (F-Actin) which is the core of the microfilaments. Actin-associated proteins which bind to actin and modify activity of microfilaments.
Microtubules
Tubulin-_ and _ isoforms alternate to form polymeric protofilament. 13 protofilaments aligned side by side make microtubule.
Desmin
Intermediate filaments for muscle cells
Vimentin
Intermediate filaments for mesenchymal cells (adult stem cells in bone marrow)
Neurofilament protein
Intermediate filaments for neuronal cells
Keratins
Intermediate filaments for epithelial cells
Glial fibrillar proteins
Intermediate filaments for glial cells (support cells in the CNS)
Four main tissue types
- Epithelial 2. Connective 3. Muscle 4. Nerve
Epithelial tissue
Line or cover organs, regulate transport of materials, and form glands. Have an apical (top or facing the ECM) and basal (bottom or facing the lumen) surface.
Connective tissue
Combination of cells and extra-cellular matrix (ECM). Form skeletal structures, provide conduit for blood vessels and nerves, provide cushoning.
Muscle tissue
3 types: 1. Skeletal-attached to skeleton for voluntary body movement 2. Smooth-Component of many organs responsible for autonomic (involuntary) visceral movement 3. Cardiac-forms walls of heart chambers
Nerve tissue
Transmits electrical signals which regulate brain function, muscle and gland activity. Composed of neurons (cells which generate and receive electrical signals) and glia (mixed population of cells that provide metabolic and structural support to neurons.
